<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>注释和页面输出</title>
</head>
<body>
  <script>
    // 单行注释
    /*多行注释*/
    // 页面写入
    document.write("<h1>标题一</h1>")
  </script>
</body>
</html>